Urinary reflux is a common finding in patients with ileal conduits necessitated by radical pelvic surgery, and knowledge of the degree to which this reflux is capable of inducing renal damage would be important in evaluating the postoperative and long-term problems experienced by these patients. To study this problem, a canine model has been developed in which the kidney is autotransplanted to the iliac fossa and urinary drainage accomplished through a pyelocystostomy, allowing free reflux of urine into the renal pelvis under bladder pressures. Renal glomerular and tubular function is then evaluated periodically, by means of inulin clearances and tubular transport of PAH respectively, and the acute and chronic effects of urinary reflux determined. In this manner, a better understanding of the various drainage procedures available following radical cancer operations might be acquired.